Conventional wavelength division multiplexing (WDM) transmitter arrays may employ semiconductor lasers as optical transmitters. The performance of WDM systems requires signal integrity from the laser sources. The wavelengths of the output signals from the WDM laser arrays may vary due to manufacturing process variations, device age, temperature, or other factors. Individual WDM lasers may have different electrical, optical, and/or thermal properties that also affect the lasers' wavelengths. Wavelength locking can facilitate signal integrity, but is difficult to do when the lasers' wavelengths vary.
One approach to provide wavelength locking has been to employ a feedback system to compare actual laser output wavelength to the target laser output wavelength. Laser output can then be adjusted to correct for deviations. In some applications, a wavelength locker is used for each laser in an array. As the number of individual optical transmitters increases, the complexity and cost for wavelength locking may also increase. What is needed is a way to provide efficient and cost-effective wavelength locking.